<para> The structural, magnetic and electrical properties of Co<formula formulatype="inline"> <tex Notation="TeX">$_2$</tex></formula>MnSi thin films grown onto n-doped Si(110) and n-Si(100) substrates were studied. The structure and magnetic properties of Co<formula formulatype="inline"><tex Notation="TeX">$_2$</tex> </formula>MnSi thin films were found to depend strongly on the annealing temperature <formula formulatype="inline"><tex Notation="TeX">$(T_rm A)$</tex></formula>. At <formula formulatype="inline"><tex Notation="TeX">$T_rm A =275hbox--350^circ$</tex> </formula>C, the Co<formula formulatype="inline"><tex Notation="TeX">$_2$</tex> </formula>MnSi films were of B2 phase with <formula formulatype="inline"> <tex Notation="TeX">$langle 100rangle$</tex></formula> texture and possessed magnetic moment on both substrates. The saturation magnetization <formula formulatype="inline"><tex Notation="TeX">$(M_rm S)$</tex></formula> of Co<formula formulatype="inline"><tex Notation="TeX">$_2$</tex></formula>MnSi thin films was found maximum at <formula formulatype="inline"><tex Notation="TeX">$T_rm A =300^circ$</tex></formula>C. Chemical reaction might occur between Co<formula formulatype="inline"><tex Notation="TeX">$_2$</tex></formula>MnSi and Si above <formula formulatype="inline"><tex Notation="TeX">$T_rm A =350^circ$</tex> </formula>C which caused nearly zero <formula formulatype="inline"><tex Notation="TeX">$M_rm S$</tex></formula> value. The current-voltage (<formula formulatype="inline"> <tex Notation="TeX">$I$</tex></formula>-<formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula>) characteristic of the Co<formula formulatype="inline"> <tex Notation="TeX">$_2$</tex></formula>MnSi thin films onto n-Si substrates was obtained linear suggesting the contacts were ohmic nature. </para>